Current methods of forming fiber reinforced corrugated channel preforms have been generally unsuccessful. A typical channel, such as an I-beam, has a web section and upper and lower flange sections. In a corrugated composite channel, the web section is not planar, but has undulations with peaks and valleys, which provides strength characteristics with particular application in aircraft because of their unique structural properties. The term "corrugated channel" refers to such a structure.
To produce a fiber reinforced composite channel, it is typical to use multiple layers or plies of fiber, with each flat ply of sufficient width and length to form the web and flanges from the same fibers. A "preform" is a group of fiber plies having the shape of the finished part, with the plies being suitably debulked and stabilized for placement in a closed mold for resin injection in accordance with a resin transfer molding process.
However, significant difficulties arise in forming a corrugated channel as when one attempts to form the undulations and flange sections from multiple fiber plies, significant wrinkling or waviness occurs particularly at the radius between the web and flange portions. Such defects are unacceptable because they provide weaknesses in the finished part.